Geography, Migration, and Human Environments

Geographic Tools: Location, Maps, and Spatial Technology

Geographers describe position on Earth using two distinct methods: absolute location and relative location. Absolute location identifies a precise place and can be expressed using latitude and longitude or a street address. Lines of latitude, also called parallels, indicate angular distance north or south of the equator, which is designated as zero degrees latitude. Lines of longitude, also called meridians, indicate angular distance east or west of the prime meridian, which is designated as zero degrees longitude. In contrast, relative location describes where a place is situated in relation to other landmarks or locations.

To represent the round Earth on a flat surface, geographers rely on map scales and map projections. A map scale indicates the ratio between distance on the map and actual distance on the ground. A large-scale map shows a small geographic area with a high level of detail, whereas a small-scale map shows a large geographic area with less detail. Because the surface of a sphere cannot be flattened without distortion, all flat map projections distort at least one spatial property, such as shape, area, distance, or direction. For example, the Mercator projection preserves local angles and shows constant compass bearings as straight lines, but it greatly exaggerates land areas near the poles.

Different map types serve distinct analytical purposes. Political maps show human-made boundaries, such as national and state borders, and often show cities. Physical maps illustrate natural terrain features, such as mountains, rivers, and elevation. Topographic maps use contour lines to represent differences in elevation and terrain steepness. On a topographic map, contour lines that are drawn close together indicate steep slopes, while widely spaced lines indicate gentle slopes. When geographers want to focus on a particular subject rather than general landscape features, they use a thematic map, which emphasizes a specific spatial topic, such as population density, climate zones, or economic activity.

Modern geographic inquiry also relies on advanced digital tools. Geographic Information Systems (GIS) integrate hardware and software to capture, store, analyze, and display layered spatial data. Meanwhile, the Global Positioning System (GPS) uses satellite signals to determine the precise absolute location of a receiver on Earth.